This invention relates to heterostructure semiconductor optical devices including tapered couplers and methods of fabricating same.
An important step for the development of monolithic integrated optical circuit components is the efficient transfer of light from one waveguide layer to another so that various circuit components, such as lasers, modulators and detectors, can be optically interconnected. One method to accomplish this transfer, utilizing tapered couplers, has been suggested by Tien et al, and their feasibility in organosilicon film waveguides has been demonstrated (see, Applied Optics, Vol. 12, p. 1909 (1973) and Applied Physics Letters, Vol. 24, p. 547 (1974)). In AlGaAs waveguides, this transfer has been effected between a passive waveguide of increased bandgap and width which is in tandem with the active layer of a double heterostructure (DH) junction laser or detector with a reduced bandgap. (See, copending application Ser. No. 481,244, Logan and Reinhart, filed on June 20, 1974) now U.S. Pat. No. 3,993,963.